Protein-bound phosphorylserine in acid hydrolysates of brain tissue. The determination of [32P]phosphorylserine by ion-exchange chromatography and electrophoresis

1. Partial acid hydrolysates of proteins derived from cortical slices of guinea-pig brain were divided into two parts and fractionated by ion-exchange chromatography and high-voltage electrophoresis. 2. The apparent yield of protein-bound phosphorylserine by the ion-exchange method was about three times that obtained by electrophoresis. 3. The specific radioactivity of phosphorylserine isolated from (32)P-labelled slices by electrophoresis was twice that isolated by chromatography. 4. The discrepancies were found to be due to the presence of unlabelled phosphates of unknown composition in the ;phosphorylserine' fraction obtained by the ion-exchange method. 5. Electrical stimulation of slices respiring in the presence of [(32)P]phosphate increased the specific radioactivity of the total phosphate in the chromatographic ;phosphorylserine' fraction by 53+/-11%, as compared with only 19+/-5% for the phosphorylserine isolated by electrophoresis.     

Male and female meiosis in grasshoppers

Male meiosis in the grasshopper Stethophyma grossum is well known as an example of proximal chiasma localisation. An investigation of female meiosis in oocytes of this species shows that both the frequency and distribution of chiasmata are quite different from the male situation. Mean chiasma frequency per cell (14.98) in considerably higher in females than in males (11.28) which agrees with the trend established in other comparative studies of male and female meiosis. More strikingly, males and females also show not only different but quite opposite patterns of chiasma distribution. In spermatocytes of males, chiasmata are strictly localised proximally in most bivalents, but in oocytes of females very few chiasmata form in proximal regions and nearly all chiasmata form either in distal or interstitial regions. The genetical significance of these findings is considered.     

Nematospiroides dubius: Mechanisms of host immunity: II. Skin testing and immunosuppression of orally or subcutaneously sensitized mice

The present study was designed to acquire further understanding of the differences in the immune response of mice orally (OS) or subcutaneously (SS) sensitized to Nematospiroides dubius. Two immunosuppressive agents and skin tests were utilized in this regard.Rabbit antimouse thymus serum (RAMTS) and cyproheptadine (antihistamine-antiserotonin) were similarly effective in suppressing the immune response of subcutaneously sensitized mice. When compared to normal rabbit serum and SS control (sensitized, untreated) animals, observations of the intestinal tunica muscularis in the immunosuppressed SS groups revealed granulomatous lesions in which fewer eosinophils enveloped the sequestered parasite. Cyproheptadine was more successful than the other treatments in interrupting the immune expulsion of N. dubius from orally sensitized mice, but this was only at a borderline significance level.The size and intensity of the active cutaneous anaphylactic skin tests in OS mice injected with an adult or larval antigen, was greater than the response elicited in SS mice or uninfected control mice injected with the same preparations. Similarly, the reaction in subcutaneously sensitized mice exceeded that observed in the noninfected controls.     

Inhibition by 1-beta-D-arabinofuranosylcytosine of the incorporation of N-acetylneuraminic acid into glycolipids and glycoproteins of hamster embryo cells

1-β-D-Arabinofuranosylcytosine which interferes with DNA synthesis in bacteria and mammalian cells and brings about transformation of hamster embryo fibroblasts, has been found to inhibit the incorporation of N-Acetylneuraminic acid into glycolipids and glycoproteins of both normal and transformed hamster embryo cells in tissue culture. Three hours after commencement of treatment (10^?3M ara-C), incorporation of [¹⁴C] thymidine into DNA was inhibited by 95 per cent, while incorporation of [³H] D-glycosamine (precursor of sialic acid) into glycolipids and glycoproteins was inhibited by 85 per cent. At 24 hours, the inhibition of incorporation of the two labelled components was 83 and 80 per cent respectively. In homogenates of both cell types, incorporation of [¹⁴C] N-acetylneuraminic acid was competitively inhibited by ara-CMP. Ara-C was found to have no effect on the incorporation of [¹⁴C] choline into phospholipids of cells grown in tissue culture. These results suggest that interference with DNA synthesis by ara-C may not be the only factor involved in cell transformation by this substance.     

Reversible binding of phytomitogens to lymphocytes

The reversible binding of phytohaemagglutinin and concanavalin A to lymphoyctes and red cells was studied by radiolabelling techniques. The quantity of mitogen bound was dependent on the temperature, concentration and duration of the mitogen pulse. Dissociation of mitogen occurred rapidly from red cells and lymphocytes and the kinetics of release from lymphoid cells displayed two components with different half lives. There was suggestive evidence that the binding component with the longer half life was related to lymphocyte activation. The induction of DNA synthesis in lymphocytes required at least 20-hr exposure to the mitogens. These data indicate that the binding of mitogen is a complex reversible process in which association and dissociation are critically dependent on the temperature, concentration and duration of the mitogen pulse.